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25 August 2009, Volume 29 Issue 04 Previous Issue    Next Issue

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Application of Truss Topology Optimization in Spacecraft Structures Engineering Li Dongze1 Yu Dengyun2 Ma Xingrui3(1 Beijing Institute of Spacecraft System Engineering,Beijing 100094)(2 China Academy of Space Technology,Beijing 100094)(3 Chinese Space Science and Technology Group Co.,Beijing 100833) 2009, 29 (04):  1-7.  Abstract ( 2004 )   Save The optimal topology design of satellite trusses with appended structures was performed.The main goal was to reduce the volume(or the weight) of the structure while satisfying the compliance and the natural frequency constraints.Semidefinite programming was used to avoid underlying difficulty of sensitivity analysis of multiple eigenvalues.The effect of stiffness and mass of appended structure on optimum topology result was presented and several optimum designs were compared with each other.Structural mass was greatly reduced using this optimization method.The second member in the optimal topology design was grouped for parameter optimization according to the engineering considerations and the final practical structure satisfying the satellite mechanical performance was obtained. Related Articles | Metrics

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Reentry Trajectory Optimization for Manned Deep Space Exploration Min Xuelong Pan Teng Guo Hailin(Beijing Institute of Spacecraft and Systems Engineering,Beijing 100094) 2009, 29 (04):  8-12.  Abstract ( 1784 )   Save A method for reentry trajectory optimization using genetic algorithm was established.The presumptive performance of the manned deep space exploration capsules like Apollo and Soyuz command modules were employed.By a Matlab optimization process,the simulation results indicate that the maximum g-load is less than 4gn.The pressure,heat density,temperature and the total heat rates decrease obviously.The flight distance is shorter than that of the un-optimal reentry trajectory. Related Articles | Metrics

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Low Energy Transfer Orbit to the Moon Considering Longitude of the Ascending Node of the Moon Lu Songtao Zhao Yushan(School of Astronautics,Beijing University of Aeronautics and Astronautics,Beijing 100191) 2009, 29 (04):  13-20+27.  Abstract ( 1975 )   Save The basic models of the transfer orbit to the Moon were mainly the restricted two-body model and the restricted three-body model.In the restricted three-body model,the trajectory based on the trajectory class theory required less fuel(save at least 13%) comparing to that of the Hohmann transfer.Sun should be considered in trajectory design,because the trajectory class theory could not be used to solve the single Earth-Moon-Spacecraft restricted three-body problem.Considering the longitude of the ascending node of the Moon,the angle of the ecliptic and Moon orbit,and the correct stable manifolds of Earth-Moon system,the whole Sun-Earth-Moon-Spacecraft system was divided into two parts: the Earth-Moon-Spacecraft planar circular restricted three-body problem,and the Sun-Earth-Spacecraft three dimensional circular restricted three-body problem.The availability of the method was verified by Matlab. Related Articles | Metrics

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Numerical Solution of TPBVP for Optimal Lunar Soft Landing Zhao Jisong Gu Liangxian Pan Lei(College of Astronautics,Northwestern Polytechnical University,Xi′an 710072) 2009, 29 (04):  21-27.  Abstract ( 2557 )   Save With the help of Pontryagin′s maximal principle(PMP),the fuel optimal lunar soft landing problem was converted into a two point boundary value problem(TPBVP) of variable final time.Initial adjoint guess technique was introduced to provide approximate initial adjoint variables by solving linear algebra equations in the neighborhood of the initial time.Linear perturbation method,which can deal with TPBVP with variable final time,was used to solve the TPBVP.Simulation results indicate that the guessed initial adjoint variables are just in the convergence regions of linear perturbation method,and the convergence rate is rapid.The optimal soft landing trajectories varied with thrust magnitude were investigated.The results show that high-thrust can not only reduce landing time,but also brake fuel consumption. Related Articles | Metrics

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Decomposed Error Quaternion-Based Rigid Body Attitude Tracking System with Sliding Mode Control Li Tiejun1,2 Huang Hai1(1 Beijing University of Aeronautic and Astronautic,Beijing 100083)(2 Beijing Institute of Electric System Engneering,Beijing 100854) 2009, 29 (04):  28-36+53.  Abstract ( 1983 )   Save A sliding mode control(SMC) method was proposed and applied to a rigid body attitude tracking system in the presence of dynamic uncertainties.First,a model of the attitude tracking system was built in terms of the decomposed error quaternion,then feedback linearization was used to obtain the required angular acceleration.The SMC algorithm was proposed to make the angular acceleration of the rigid body track the required angular acceleration.Simulation results show that the proposed SMC law is globally stable and insensitive to the uncertainties and variations in its inertial parameters,and control actuator aligment and external disturbances. Related Articles | Metrics

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Autonomous Determination of Relative Orbit for Satellite Formation Flying Using Radio-only Measurement Wang Hui Gu Xuemai(Harbin Institute of Technology,Harbin 150001) 2009, 29 (04):  37-45.  Abstract ( 1887 )   Save In practical applications,some measurement equipment(such as laser) of satellite formation flying can not be used for mission requirements,which led to the decline in observability.The condition number was used in quantitative calculation of the observability in satellite formation flying system.For satellite formation flying orbit adjustment situation,which only used radio measurement,a strong tracking unscented Kalman filter(UKF) algorithm was introduced to the simulation.The results show that the method has strong tracking capability,robustness and stability.Moreover,a strong tracking UKF algorithm has similar accuracy with that of the normal UKF algorithm. Related Articles | Metrics

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Orbit Configuration Design and Perturbation Analysis Based on Formation Flying InSAR Satellites Mission and Performance Requirements Li Yang1 Zhang Running2(1 Institution of Communication Satellite,China Academy of Space Technology,Beijing 100094)(2 Dong Fang Hong Satellite Co.Ltd,Beijing 100094) 2009, 29 (04):  46-53.  Abstract ( 2093 )   Save Configuration design is of great importance to the formation flying InSAR satellites system.To achieve specific spatial baseline form when the satellites are flying over the specific Earth surface,the formation configuration is the only variable which can be designed freely,while other parameters are restricted by many limiting factors.The formation flying model based on orbit perturbation solution was studied.The orbit design constraint conditions and objective of formation flying InSAR satellites were analyzed.Four two-satellite formation proposals and comparisons of their elevation generation performances were presented.The influence of the earth flattening perturbation to the formation configuration and the InSAR measurement performance were also described. Related Articles | Metrics

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Numerical Study on Space Outer-heat Simulator Manner with Infrared Thermal Club Yang Xiaoning Ren Depeng Jia Yang(China Academy of Space Technology,Beijing 100094) 2009, 29 (04):  54-60.  Abstract ( 1586 )   Save Emission and absorption in energy bind can be traced by Monte Carlo method.A new method named equivalent reflection model was developed to avoid calculating the board surface energy equation.Energy distributing and other parameters on cold surface of space outer-heat simulator with infrared thermal club were simulated by the method,and the simulation results on straight and bend clubs were compared.The result shows that energy distribution changes little with the surface emissivity changed by replacing the internal and external surface of the board,and the cold surface energy distribution can not keep uniform by adding thermal clubs.Heat distribution of the bend club is better than that of the straight one. Related Articles | Metrics

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Steady-state Characteristics of a Closed-loop Spray Cooling System Zhang Hongxing Miao Jianyin Yao wei Shao Xingguo Fan Hanlin(Beijing Institute of Spacecraft System Engineering,Beijing 100094) 2009, 29 (04):  61-68.  Abstract ( 2058 )   Save A visual closed-loop spray cooling test system was established for high heat flux cooling,with which the experimental phenomena in the visual chamber could be directly observed.The steady-state characteristics of the spray cooling system were investigated.In the test,the spray cone,angle,atomization effect,liquid film on the heat rejecting surface,and vapor/liquid interface in the spray chamber could be observed through the visual shell of the spray chamber.The effects of the heat flux value,the spray distance,the sink temperature,the subcooling degree of the return liquid on the heat transfer performance and the evaporation efficiency of the spray liquid were analyzed. Related Articles | Metrics

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Interference Effects on BOC Signals Wang Lu Liu Chonghua He Shanbao(China Academy of Space Technology,Beijing 100094) 2009, 29 (04):  69-76.  Abstract ( 1859 )   Save The binary offset carrier(BOC) signals,a new kind of signal used for navigation,were compared with traditional PN code navigation signals.The anti-jamming performance of BOC signals was analyzed by building a mathematical model of BOC signal receiver system.Three radio frequency(RF) interference signal models including carrier wave(CW) interference,matching-spectrum interference and limited-band Gaussian interference were researched.Some anti-jamming performance parameters of navigation signals already used in GPS and Galileo systems were also given.The result shows that BOC signals have a smaller effect on interference than that of the classical spread spectrum navigation ones. Related Articles | Metrics

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Task Scheduling Optimization Design for Micro-satellite Based on Load Balancing Yao Min Zhao Min(College of Automation Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016) 2009, 29 (04):  77-83.  Abstract ( 2000 )   Save In the Dual-computer Hot-backup working pattern of micro-satellite,if the on-board computers work in parallel,it can improve the efficiency of the system.According to the actual tasks of micro-satellites,a scheduling method based on genetic algorithms was presented to reduce tasks time consumption and balance the load in the onboard computers.However,reducing tasks time consumption and balancing load are incompatible in some cases.In the fitness function of genetic algorithms,the parameters of reducing tasks time consumption and balancing load were considered,quantized and assigned with the same weighted value.By this way the comprehensive performance of the Satellite Keeping Operator(STO) was improved. Related Articles | Metrics